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3D Model Helps Set Stage for Gay Head Light Relocation

The committee to save the Gay Head Light is going three dimensional in its preparations for relocating the old lighthouse.

In October, the committee received a grant from Meridian Associates, a land surveying and civil engineering firm in Beverly that specializes in 3D laser scanning modeling. The company visited the lighthouse last week with a laser scanner to generate an accurate 3D model of the lighthouse, chairman of the lighthouse building committee Lenny Butler said, adding that there is no structural plan of the lighthouse as it exists today.

“They scanned the building inside and out and it will produce a 3D model that is accurate within a centimeter,” Mr. Butler said. “It will be a useful tool for engineering because the structural engineers can look at it and see where the stressers are and calculate the move.”

The engineers will also be able to model any reactions the structure may have during the move, Mr. Butler said.

“We now have a record as-built,” he said. “If there’s any alterations or damage during the move, we can replicate what was original.”

The company has done similar laser imaging for historic preservation sites including the U.S.S. Constitution, the Isabella Stewart Gardner Museum and the Straitsmouth Island Lighthouse in Rockport.

Visitors to the lighthouse website will be able to take a virtual tour of the building. The image should be available in the coming weeks.

Three sites near the lighthouse are being studied to better understand the soil structure and select which lot is best for the relocation. The town recently received approval from the Coast Guard to perform geotechnical borings on site, Mr. Butler said. Approval has also been granted from the state historic preservation office and the Wampanoag Tribe of Gay Head (Aquinnah). The drilling will begin sometime in the new year and will be conducted by GEI Consultants.

“That data will help us determine the suitability of the various sites in terms of the geology for its sustainability and supportability for the weight of the structure,” Mr. Butler said.

On August 1 the Coast Guard designated the lighthouse as surplus property under the National Historic Lighthouse Preservation Act, and the town of Aquinnah is currently writing an application to take ownership of the light. Aquinnah was one of five parties to submit letters of interest. Of the five, two are considered viable: the town and Historically Significant Structures Inc., a Philadelphia nonprofit that previously obtained ownership of a lighthouse on Long Island, N.Y. The National Park Service will review the applications and make a recommendation to the GSA. Applications are due Feb. 5, 2014.

“It’s a very involved and intensive application where they want to know what you’re restoring, what your preservation plans are, the management plan and financial plan for doing all of this, as well as what the public acceptability will be,” Mr. Butler said.

One thing that has been settled is the future of the sweeping light itself. In June, the Coast Guard announced it had abandoned plans to replace the optic with a pulsing LED light. After public outcry and a search of Coast Guard warehouses, the Coast Guard said it found a replacement rotating optic for the aging lens. The current optic was installed in 1989 and requires regular maintenance.

“They’ll get as many miles out of this one until it breaks down and then we have one in reserve,” Mr. Butler said.

The Save the Gay Head Light Committee hosts a winter solstice celebration at the lighthouse with food, music and tours from 3 p.m. to 5 p.m. on Saturday, Dec. 21. For information visit gayheadlight.org.

This appears to be a brick structure, so determining amount and location of reinforcing steel is not a problem. I'm curious how 3D laser scanning would produce as-builts of reinforced concrete structures.